Sound modes in collisional superfluid Bose gases

Abstract

We theoretically investigate sound modes in a weakly-interacting collisional Bose gas in $D$ dimensions. Using the Landau's two-fluid hydrodynamics and working within the Bogoliubov theory, we observe the hybridization of the first and second sound modes for $D\ge 2$. To model the recent measurements of the sound velocities in 2D, obtained in the weakly-interacting regime and around the Berezinskii-Kosterlitz-Thouless transition temperature, we derive a refined calculation of the superfluid density, finding a fair agreement with the experiment. In the 1D case, for which experimental results are currently unavailable, we find no hybridization, triggering the necessity of future investigations. Our analysis provides a systematic understanding of sound propagation in a collisional weakly-interacting Bose gas in $D$ dimensions.

14 pages, 8 figures, accepted for publication in New Journal of Physics

References in corpus (6)

• Observation of scale invariance and universality in two-dimensional Bose gases
• Superfluid behaviour of a two-dimensional Bose gas
• Ground state energy of the two-dimensional weakly interacting Bose gas: First correction beyond Bogoliubov theory
• First and second sound in a strongly interacting Fermi gas
• Universal thermodynamics of a two-dimensional Bose gas
• Finite-Range Corrections to the Thermodynamics of the One-Dimensional Bose Gas

Cited by in corpus (1)

• First and second sound in two-dimensional bosonic and fermionic superfluids